1. Field of the Invention
The present invention is directed to a machine for fabrication of roof trusses. More particularly, the present invention is directed to such a machine that is controlled by a joystick.
2. Description of The Related Art
Pitched roofs are commonly supported by roof trusses. Roof trusses are commonly constructed of wood, particularly for wood-framed structures and residences. Roof trusses are manufactured in a wide variety of shapes and sizes according to the needs encountered in erecting a specific building. Because the roof line is usually fairly uniform throughout much of the length of a single building, many identical trusses are needed for a single building.
It has long been known that such trusses can be fabricated more efficiently through use of a truss table than they can by manual methods at the job site. The truss table is setup so that each precut piece of a particular truss fits into a channel created by parallel raised members fastened to the top of the truss table. When all the pieces for a single truss have been put in place on the truss table, they are fastened together. Nails, staples, and other similar fasteners have long been used. For some time, it has been common practice to fasten many of the joints, particularly those bearing greater loads, with connector plates, which consist of a flat plate having a large number of downward projecting parallel spikes generally created by pressing a flat plate within a specially designed die. A connector plate is seated on both the top and bottom sides of the joint as the truss lies on the truss table.
The connector plates may be seated by hammering or the like. Substantial forces are required to seat the connector means of a machine. Such a truss fabricating machine is disclosed in U.S. Pat. No. 3,826,188, issued to George F. Eberle on July 30, 1974.
Eberle '188 discloses a truss table having a hydraulic press for seating connector plates. The press reciprocates up and down on command and is located above the top of the truss table. A gantry carries the press along a set of parallel rails table and parallel to the transverse or Y dimension, direction, or axis of the table and perpendicular to the long, or X dimension, or direction, or axis of the truss table. One mechanism allows the press to be moved along the gantry itself, that is, along the Y-axis. Another mechanism allows the gantry to be moved along the X-axis, thereby allowing an operator who stands on an operator's platform at the end of the gantry to move the press to any desired location, then to actuate it, causing the press to stroke down with great force and to seat the connector plates which have been previously placed in position on the truss table and truss members on both the top and bottom of the truss members. An anvil located underneath the truss table and fixed to the gantry masts provides support for the press during pressing, thereby preventing the press from breaking the truss and the table.
The device of Eberle '188 suffers from several disadvantages. First, it requires the skillful manipulation of at least three different hydraulic control levers whose different functions must be learned by the operator. These control levers require considerable force to move and do not provide a precise response to the operator's touch. Further, although it is possible to move the press along both the X-axis and the Y-axis simultaneously, it requires a highly skilled operator using both hands to do so and he must concentrate clearly on the job at hand at all times. Consequently, the operator frequently fails to locate the press directly above a particular connector plate on the first try, but must repeatedly make second and third efforts. This repetition leads to decreased productivity and accelerated wear on the equipment.
Accordingly, there is a need for a truss fabricating machine which seats connector plates that is easier to control than truss fabricating machines of the prior art; that is more responsive to the operator s touch; that allows the operator to control all movement of the press with one hand; that is intuitive to use because the movement of the press mimics the movement of the operator s hand; and that allows the press to be easily and accurately moved along both the X-axis and the Y-axis simultaneously.